WO1996014342A1 - Process for producing starch ester, starch ester, and starch ester composition - Google Patents

Abstract

A process for producing a starch ester by the reaction of starch with a vinyl ester having a C2-C18 ester group in the presence of an esterification catalyst in a nonaqueous organic solvent. The esterified starch is biodegradable, has high degree of substitution, molecular weight and water resistance, and gives molded articles extremely excellent in mechanical strengths and physical properties.

Description

 Specification

Method for producing starch ester, starch ester, and starch ester composition

Background technology

 The present invention relates to a method for producing a starch ester produced by using a vinyl ester as an esterification reagent, a starch ester, and a composition containing the starch ester. In particular, the present invention relates to a method for producing a starch ester capable of obtaining a water-resistant starch ester having a degree of substitution, a molecular weight, and a mechanical strength, a starch ester, and a starch ester composition.

 As a synthesis reaction suitable for obtaining a starch ester having a low substitution degree (DS 1.0 or less), a method using vinyl acetate as an esterification reagent in an aqueous slurry state is known. ("Starch Science Handbook", published by Asakura Shoten Co., Ltd., first published in July 1997, first edition, page 505)

 On the other hand, as a synthesis reaction suitable for obtaining a starch ester having a high degree of substitution, a method is known in which an acid anhydride is reacted in pyridine with dimethylamino pyridine or an alkali metal salt as a catalyst. (See “Starch Schema History & Technology,” Whistler, published by ACADEMIC PRESS, pages 332-336.)

Another method for producing high-substituted starch esters is to react with an aqueous solution of an alkali metal hydroxide in an acid anhydride at a temperature of 100 ° C or higher, and purify with alcohol. A method for carrying out the method and a starch ester thereby are known. (Japanese Patent Application Laid-Open No. 5-50881) Further, in the same application, the produced starch ester and its specific effect on the starch ester (the effect of causing the starch ester to gel). And compositions with a plasticizer having the formula: One further response to the production of highly substituted starch esters is described in AMMark and Mehltretter, published in the academic journal “Die Starke J (March, page 73)” in 1972, A method very similar to 508 185 is known.

 However, in the above method for producing a highly substituted starch ester, the effective utilization of the esterification reagent is as low as about 40%, and the amount of the by-produced organic acid and a small amount of water or catalyst present in the diluting solvent are reduced. The water added into the system hydrolyzes the glucosidic bond (mainly αΐ-4 bond) of the resulting starch ester to form a low molecular weight starch ester, or some other method. Even if the lowering of the molecular weight is prevented as much as possible, the molecular weight of the starch ester formed does not become larger than the molecular weight of the starch used as a raw material as stoichiometrically considered.

 Therefore, there is a method in which an alkaline salt such as sodium bicarbonate is preliminarily mixed into the reaction solvent in order to prevent the reduction of the molecular weight (hydrolysis), but the molecular weight is also reduced to about 1-3. It is not very effective.

 Furthermore, the starch esters produced by the above-mentioned various known methods (eg, Japanese Patent Application Laid-Open No. 5-508185, the method of synthesizing starch esters of AMMark and C. L. ehltretter, etc.) have water resistance, mechanical properties, etc. In the above, as a starch derivative, a corresponding molded article can be made, but practically,

 1) Higher mechanical strength and mechanical properties

 2) lower water (or water vapor) sensitivity

 (That is, there is little effect on mechanical properties by water or moisture in the air.)

3) cheaper manufacturing cost

Is required.

In particular, regarding point 3), the efficiency of the esterification reagent The conventional technology has its limits, and its cost has naturally been limited.

 In addition, in the case of high-substituted starch esters produced by conventional methods (using fatty acid anhydrides or fatty acid halides), biodegradable polyester, polyvinyl alcohol (PVAL), vinyl acetate (PVAC), cellulose acetate Blending with, etc., a corresponding improvement in mechanical properties can be seen, but a change in strength indicated by a straight line connecting the mechanical strength of the molded product with starch ester alone and the mechanical strength of the molded product with other resin alone Compared to the process, the mechanical strength of molded articles made from blends of starch esters and other resins tended to be lower (see Application Example 2 and Comparative Application Example 2). These are considered to be due to the miscibility (compatibility) between the starch ester produced by the conventional method and the resin. The differences in compatibility are not yet clear at this time, but the fundamental differences in the molecular structure of starch esters are: molecular weight, intramolecular distribution of ester substituents, compatibility of starch esters with plasticizers, It is thought to be due to differences in the maximum retained amount of starch ester plasticizer, and the shear viscosity related to the molecular weight and the maximum retained plasticizer amount. There has been a strong demand in the industry for the appearance of water resistant, biodegradable, and thermoplastic starch esters or starch derivatives that do not tend to decrease mechanical properties as described above or that are extremely low. Disclosure of the invention

Method for Producing Starch Ester of the Present Invention As described above, starch ester is a vinyl ester having an ester group carbon number of 2 to 18 and reacted with starch using a esterification catalyst in a non-aqueous organic solvent. Further, a composition comprising these starch esters and at least one or more ester-type plasticizers having high compatibility with the starch esters as a main component is provided. The following effects are observed as supported by the following examples and comparative examples.

1) Efficacy of esterification reagent is 50% or more.

 2) The starch ester composition can form a molded article having remarkably high mechanical strength as compared with the conventional starch ester composition. This is because, despite the fact that the resulting starch ester has a surprisingly low degree of substitution, it has a high molecular weight that cannot be achieved by the conventional method, ie, the raw starch used in the reaction (unmodified starch, This is thought to be due to the increase in molecular weight due to esterification, rather than mildly modified starch).

 3) Furthermore, the starch ester produced is completely different from the starch ester produced by the conventional method, and the mechanical strength of the composition obtained by combining with the above-mentioned synthetic resin and plasticizer is good. It shows mechanical strength corresponding to the compounding ratio, or mechanical strength higher than expected from the compounding ratio, due to its high miscibility (compatibility). This means that the starch ester of the present invention is a novel starch ester having a different molecular property and a different molecular structure from the starch ester produced by the conventional method.

 Furthermore, when vinyl ester is used as the esterification reagent and at the same time as the reaction medium (reaction solvent), a special solvent recovery step in the production step is not required, and the efficiency of inhibiting the reduction of molecular weight is increased. BRIEF DESCRIPTION OF THE FIGURES

 Fig. 1

Graph showing the relationship between starch ester / polycaprolactone blend ratio and tensile strength Fig. 2

 FIG. 1 is a graph showing the relationship between the blend ratio of starch acetate and cellulose acetate and the tensile strength.

 Hereinafter, the present invention will be described in detail. Here, the blending unit is a weight unit unless otherwise specified.

 (1) Raw starches for esterified starch include: (1) unmodified starches such as corn starch, high amylose corn starch, wheat starch, etc .; (2) unmodified starches such as potato starch, tapi flour starch, etc .; Low-esterification, etherification, oxidation, acid treatment, dextrinized modified starch, etc. are used alone or in combination.

 (2) As a vinyl ester as an esterification reagent, an ester group having 2 to 18 carbon atoms (preferably 2 to 7 carbon atoms) is used alone or in combination. When the number of carbon atoms in the ester group exceeds 18, the efficiency of the reagent increases, but the reaction efficiency decreases. Further, when the number of ester-based carbon atoms is in the range of 2 to 7, a high level can be maintained in terms of reaction efficiency (70% or more).

 Specifically, the following can be exemplified (the number in the parentheses is the number of carbon atoms in the ester group). Of these, vinyl acetate and vinyl brobionate are particularly preferred because of their high reaction efficiency.

(1) Vinyl acetate (C 2), vinyl propionate (C 3), vinyl butanoate (C 4), vinyl caproate (C 6), vinyl cabrate (C 8), lau, vinyl acetate (C 12) ), Vinyl palmitate (C 16), vinyl stearate (C 18), etc .; or vinyl acrylate (C 3), vinyl crotonate (C 4), biisocrotonate Unsaturated fatty acids such as nil (C 4) and vinyl oleate (C 18)

 (2) Vinyl benzoate, vinyl ester of aromatic carboxylic acid such as P-methyl vinyl benzoate) can be used.

 (3) One embodiment of the non-aqueous organic solvent is when vinyl ester is used as the organic solvent.

 In this case, a special solvent recovery step in the purification step becomes unnecessary. In the esterification reaction using a conventional vinyl ester, such a reaction format is not adopted.

 In addition, in the case of this embodiment, the effect of preventing the reduction of the molecular weight and the reaction efficiency of the vinyl ester are improved, which is desirable. On the other hand, the vinyl ester is limited to a liquid (including a heated and melted one). Has reaction heterogeneity.

 Examples of the vinyl ester that can be used for this include the vinyl esters described in the preceding section.

 (4) The other embodiment of the non-aqueous organic solvent is when vinyl ester as a reaction reagent cannot be used or is not used as the non-aqueous organic solvent.

 Regardless of the type of vinyl ester, it has the advantage that the reaction solution concentration and reaction rate can be easily adjusted.The reaction uniformity is higher than when vinyl ester is used as an organic solvent, but the vinyl ester Separation and recovery from the solvent is required.

In this case, the non-aqueous organic solvent includes: (1) a vinyl ester converted to a starch-soluble polar solvent such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or pyridine; or (2) a starch such as ethyl acetate / acetone. Insoluble and also vinyl ester 'formed ester Polarized solvents that are soluble in starch (but not reactive with vinyl ester) can be used alone or in combination.

 In particular, starch-soluble non-aqueous organic solvents such as DMSO, DMF, and pyridine are preferable from the viewpoint of reaction efficiency and reaction uniformity.

 (5) Examples of the esterification catalyst include: (1) an alkali, alkaline earth, amphoteric metal hydroxide and / or mineral acid salt, carbonate or organic acid salt, (2) an organic interlayer transfer catalyst, and (3) Amino compounds are used by selecting from any of the groups. Of these, ① is desirable from the viewpoint of reaction efficiency and catalyst cost.

 (1) Alkali metal hydroxides such as caustic soda, caustic calcium, and lithium hydroxide;

Alkali metal organic acid salts such as sodium acetate, sodium propionate and sodium toluene sulfonate; alkaline earth metal hydroxides such as barium hydroxide and calcium hydroxide, calcium acetate, calcium bromide, P Alkaline earth metal organic acid salts such as barium toluenesulfonate; mineral acid salts such as sodium phosphate, calcium phosphate, sodium bisulfite, sodium bicarbonate, calcium sulfate, sodium aluminate, potassium zincate, aluminum hydroxide Acid salts and hydroxides of amphoteric metals such as zinc hydroxide and carbonates such as sodium carbonate and potassium bicarbonate.

 (2) Amino compounds such as dimethylamino pyridine and getylaminoacetic acid.

 (3) N-trimethyl-quaternary ammonium compounds such as N-propylammonium chloride and N-tetraethylammonium chloride.

(6) The above catalysts can be pre-impregnated with starch in advance of production to improve the reaction efficiency when the reaction is carried out in a vinyl ester medium or in a non-aqueous medium in which starch is not dissolved. desirable. Examples of the pretreatment method of impregnating the starch with the catalyst include a method in which the raw starch can be rendered into an aqueous solution or solvent containing the catalyst, a method in which the starch and the aqueous solution or the solvent containing the solvent are mixed with a kneading device such as a kneader, or a catalyst. An aqueous solution containing a solvent may be prepared by various methods such as a method of converting a solvent and starch into a starch by a starch dryer such as a drum dryer, a method of gelatinizing and impregnating an aqueous solution containing a catalyst or a solvent and a starch with a batch cooker or a continuous cooker, and the like. An impregnation method can be adopted.

 (7) The reaction temperature condition in the present invention is not particularly limited, but is usually 30 to 200 ° C, preferably 60 to 150 ° C from the viewpoint of reaction efficiency.

 In a conventional reaction using an acid anhydride, a temperature condition of 4 O'C or less was adopted in order to prevent a reduction in the molecular weight (hydrolysis) of starch. Since there is no by-product, the reaction can be carried out at such a high temperature, and the reaction efficiency can be increased. The amount of the vinyl ester used as the esterification reagent is 1 to 20 moles, preferably 3 to 7 moles, per 1 mole of the raw starch.

 The amount of the esterification catalyst to be used is usually 1 to 30% per starch anhydride.

 (8) The following plasticizers U (mainly ester type) can be used as plasticizers having high compatibility with starch esters.

 • Phthalates: Phthalates such as dimethyl, getyl, dibutyl, etc., and ethyl phthalyl glycolate, butyl phthaloyl butyl glycolate, etc.

'' Fatty acid esters: oleic acid, adipic acid, stealine Methyl, ethyl, butyl, iso-propyl, etc.

 Polyhydric alcohols: sucrose acetate, diethylene ester glycol dibenzoate, triacetin (triacetyl glycerin), tributane pionin (tripropionyl glycerin), acetyl glycerin, etc. Methyl acid, triethyl acetyl citrate, etc.

 Phosphate ester Triptyl phosphate, trifluorophenyl phosphate, etc.Epoxy plasticizer Epoxidized soybean oil, epoxidized castor oil, alkyl epoxy stearate, etc.High-molecular plasticizers Various liquid rubbers, terbenes, linear polyesters, etc.

 Of these, ester-type plasticizers such as triethyl acetyl citrate (ATEC), ethyl phthaloyl ethyl glycolate (EPEG), triacetin (TA), and tributyl pionin (TP) are particularly preferred. Used well. This is because TA and TP have particularly good compatibility and high resin transparency, and ATEC and EPEG have good compatibility and particularly high mechanical strength.

 (9) The following types of fillers can be used as a filler used when manufacturing molded articles.

 • Inorganic fillers: talc, titanium oxide, clay, chalk

, Limestone, calcium carbonate, mica, glass, diatomaceous earth, wollastonite, various silica salts, various magne Shim salt, various manganese salts, etc.

 • Organic fillers: starch (including derivatives), cellulose fiber (including derivatives), cellulose powder (including derivatives), wood flour, pulp, bican fiber, cotton flour, cereal hull, cotton linter, wood fiber, pagasu etc

 • Synthetic fillers: Glass fiber, urea polymer, ceramic, etc. In particular, inorganic fillers such as talc, mica, calcium carbonate, etc., and organic fillers such as fibrous cellulose powders, cotton linter parve, bican fiber, etc. are preferably used. it can. Because talc and mica have good surface properties and no decrease in mechanical strength is seen, inorganic fillers such as calcium carbonate have good flowability during injection molding, and fibrous cell mouth etc. This is because the organic filler has a particularly high effect of improving mechanical strength.

 (10) As other natural or synthetic resins for forming a composition together with the starch ester, those exemplified below can be suitably used.

 In one embodiment of the composition preparation, the starch ester is mixed with a plasticizer as required, and the resin and filler and the like are blended with a Henschel mixer, then mixed with a blast mill or an extruder. A method of kneading may be used, but is not particularly limited.

 The resin to be blended is exemplified below, and the form may be any of powder, pellet, flake, and granule.

 '' Cellulosic: Cellulose acetate, hydroxyethyl cellulose, propylcellulose, hydroxybutylcellulose, etc.

• Polymer type: polycaprolactone, polylactic acid, polyethylene Biodegradable polyesters such as dipate, polyhydroxybutyrate (polyhydroxyalkanoates), polyhydroxybutyrate ballet, polyalkylene oxides such as polyethylene oxide and polypropylene oxide, PVA L and various modified PVAL, polyacrylamide resin, polycarbonate resin, polyurethane resin, vinyl polymer such as vinyl polyacetate, poly (vinyl carbazole), polyacrylic acid ester, ethylene vinyl acetate copolymer, etc. Example>

 A. Hereinafter, examples performed together with comparative examples to confirm the effects of the present invention will be described.

 Example 1>

 Suspend 25 g of high amylose corn starch in 200 g of DMS O (non-aqueous organic solvent), raise the temperature to 80 ° C with stirring, and gelatinize by holding at 80 ° C for 20 minutes. . Add 20% of sodium bicarbonate (catalyst) to this solution, add 12 g of vinyl acetate (vinyl ester) at 80 ° C, and react at that temperature for 1 hour. Thereafter, the reaction solution is poured into tap water, and crushed and washed with high-speed stirring to obtain a starch ester precipitate. This is filtered and dried to prepare a starch ester.

Example 2> In Example 1, 14.4 Og of butyl citrate is used as the vinyl ester instead of vinyl acetate.

 Example 3>

 In Example 1, 32 g of vinyl laurate was used instead of vinyl acetate as the vinyl ester.

 Example 4>

 In Example 1, 13.7 g of vinyl acrylate was used instead of vinyl acetate as the vinyl ester.

 Example 5>

 In Example 1, 19.8 g of vinyl benzoate is used as the vinyl ester instead of vinyl acetate.

 Example 6>

 In Example 1, 1.4 g of dimethylaminoviridine is used as a catalyst instead of sodium bicarbonate.

 Example 7>

 In Example 1, the reaction temperature was changed to 20 ° C, 40 ° C, 100 ° C, and 120 ° 150.

 Example 8>

 This example aims at synthesizing a starch ester basically similar to that of Example 1, but is an example in which a starch is pre-impregnated with a catalyst. 25 g of high amylose corn starch, 1.5 g of caustic soda and 8.3 g of water are put in a sigma blade kneader and kneaded at 30 ° C for 30 minutes. Next, after gelatinizing it by the method of Example 1, 12 g of vinyl acetate was added and reacted for 1 hour while maintaining the temperature at 8 CTC. Thereafter, the same treatment as in Example 1 is performed to obtain a starch ester.

Example 9> The purpose of this example is to synthesize a starch ester basically similar to that of Example 1, but using vinyl ester as a non-aqueous organic solvent.

 Suspend 25 g of high amylose corn starch and 7.5 g of potassium acetate in 14 g of vinyl acetate and react at 78 ° C for 4 hours. Thereafter, the same treatment as in Example 1 is performed to obtain a starch ester.

 Example 10>

 In this example, starch was impregnated in advance with a catalyst intended to synthesize a starch ester basically similar to that in Example 1, and vinyl ester was used as a non-aqueous organic solvent.

 25 g of high-amylose corn starch, 2.5 g of sodium carbonate and 7.5 g of water are put into a sigma blade unit and kneaded at 3 CTC for 15 minutes. Thereafter, the mixture is transferred to a reaction flask, 6 Og of vinyl acetate is added, and the mixture is reacted for 2 hours while maintaining the temperature at 75 ° C. Thereafter, the same treatment as in Example 1 is performed to obtain a starch ester.

 Comparative Example 1>

 This is a comparative example with respect to Example 1 in which acetic anhydride was used as an ester reagent in order to obtain the same starch ester as in Example 1.

 Suspend 25 g of high amylose corn starch in 200 g of DMSO, raise the temperature to 80 with stirring, and gelatinize by holding at 8 CTC for 20 minutes. To this solution was added 39 g of sodium bicarbonate to neutralize the acid by-produced, and then cooled to the reaction temperature of 20 ° C, and 48 g of acetic anhydride was added to the reaction solution to suppress the acid hydrolysis of starch. Add while maintaining the temperature between 20 ° C and 25 ° C. After the addition is completed, react at that temperature for 1 hour. Thereafter, a starch ester is obtained in the same manner as in Example 1.

Comparative Example 2> In Comparative Example 1, propionic anhydride is used instead of acetic anhydride. That is, this is a comparative example with respect to Example 2.

 Comparative Example 3>

In Comparative Example 1, changing the reaction temperature to 2 CTC, 40 ° C, 1 00 ° C, 1 2 0 ° C, 1 50 e C. That is, this is a comparative example with respect to the third embodiment.

 Comparative Example 4>

 This is a comparative example with respect to Example 1 in which water was used as a reaction solvent in order to obtain the same starch ester as in Example 1.

 Suspend 25 g of high amylose corn starch in tap water to make a 20% starch slurry. Add caustic soda to bring the pH to 10. Thereafter, the temperature of the slurry is adjusted to 40 ° C., and while maintaining the pH at 9 to 10, 12 g of vinyl acetate is added, and the mixture is reacted at that temperature for 1 hour. The reaction solution becomes paste-like, and it is difficult to separate and filter. The solution is poured into about 50 Oml of methanol, and the precipitate is collected and dried.

 Comparative Example 5>

46 g of high amylose starch (amylose content: 70%) is placed in a 1 L 4-flask equipped with a reflux condenser, a dropping funnel and a thermometer, and 15 Oml of acetic anhydride is added with stirring. Subsequently, heat is applied until a constant reflux occurs. Boiling temperature is about 125 ° C. At this time, it is necessary to avoid heating that causes burning of the solid starch at the bottom of the flask. After 1-2 hours, the viscosity increases and after 3-4 hours a viscous, brownish, clear mixture forms. After about 5 hours, the required reaction time, 5-1 Oml of acetic acid is distilled off at 118 ° C, followed by dropwise addition of 2 Oml of ethanol. Stir for a further 30 minutes with slightly reduced heating, then The solvent mixture consisting of acetic acid ester and acetic acid formed by the reaction between ethanol and acetic anhydride is separated at 102 to 105 ° C. The heating is then stopped and the mixture is cooled for 0.5 to 1 hour. Subsequently, 2 Oml of ethanol is again added dropwise. Then, gradually precipitate with about 20 Oml of methanol. The product is washed several times with alcohol, separated by suction and dried in air.

 B. The starch esters obtained in each of the examples and comparative examples were subjected to the following physical property tests. The results are shown in Table 1. It can be seen that each example is superior to each corresponding comparative example in any of the reagent reaction efficiency / effectiveness, the degree of substitution (DS), and the number average molecular weight. That is, the method of the present invention provides an esterification reagent having an effective rate of 50% or more, a reaction rate of 77% or more, and a high-substituted starch having a DS of 2.0 or more while preventing the resulting starch ester from being reduced in molecular weight. It can be seen that esters can be produced.

 (1) Reagent reaction rate: The amount reacted in the added esterification reagent.

 (2) Reagent efficiency: The ratio of the portion of the esterification reagent that contributes to the esterification reaction to the total molecular weight.

 (3) Degree of substitution · 'The percentage of all reactive hydroxyl groups at positions 2, 3, and 6 present in the glucose unit in the starch that show that they have been converted to ester bonds. A state in which all the substitution degrees 3 have changed (100%).

(4) Number average molecular weight: M _n = ∑ H '(∑ H,)

 Here, H i is the concentration of i-molecules in the liquid, Mi is the molecular weight of i-molecules in the liquid, and is one of the methods for indicating the molecular weight of starch as measured by gel permeation chromatography (GPC) chromatography. It is calculated by the above equation.

C. Next, various plasticizers were added to the starch esters of the present invention and comparative examples. Next, a test was conducted on the relationship between the mixing ratio and the strength of the molded product when various resins were mixed.

 Application Example 1Comparative Application Example 1>

 Using each high-molecular-weight starch ester having a degree of substitution of 2.5 (both the former and the latter) prepared by the method of Example 1 and Comparative Example 5, respectively, and triethyl acetyl citrate (ATEC) as a plasticizer, a table was prepared. Test pieces of Application Example 1 and Comparative Application Example 1 were prepared from the mixture prepared according to the formulation shown in 2, and the tensile strength (JIS K 7113; type 1 test piece) and bending strength (JIS K 7203) were determined. It was measured.

 From Table 2 showing the test results, in the plasticizer compounding formulation, application example 1 using Example 1 was compared to comparative application example 1 using Comparative Example 5 regardless of the amount of the compounding amount. It can be seen that the mechanical strength is remarkably excellent.

 Application Example 2Application Comparison Example 2>

 Each of the high-molecular-weight starch esters having a degree of substitution of 2.5 (former) or 2.1 (latter) prepared by the method of Example 1 and Comparative Example 1 and triacetin as a plasticizer was used. In the formulation shown, the mixture was prepared by mixing Borica Brolactone (“T0NE-787J” manufactured by Union Carbide Co., Ltd.) or “Acetate Tenex 0660 J” manufactured by Cellulose Acetate (Teijin Co., Ltd.) as a blend resin. Application Example 2 · Test pieces of Comparative Application Example 2 were prepared, and the tensile strength (JIS K 7113; type 1 test piece) was measured.

From Table 3 and Figs. 1 and 2 showing the test results, the relationship of the mechanical strength of the plasticizer compound is on the linear relationship L in the case of the application example 2 of the present invention, whereas the relationship of the comparative application example 2 is In the case of, it can be seen that the line graph is bent downward. Application Example 3Comparative Application Example 3>

 Example 1 and Comparative Example 3 (starch ester having a degree of substitution of 2.5 (former) or 2.3 (former)) prepared by the method of reaction temperature (100 ° C.), respectively, and triethyl acetyl citrate (AT) as a plasticizer. EC), ethylphthaloylethyl glycolate (EPEG), triacetin (TA), and dibutylphthalate (DBP), respectively (17.6 parts of starch as a plasticizer). Test pieces of Application Example 3 and Comparative Application Example 3 were prepared from talc containing 3 Owt% as a filler, and the flexural modulus (JIS K 7203) and flexural strength (JIS K 7203) were measured.

Table 4 shows the results.In the case of Application Example 3, further improvement in mechanical strength can be seen by changing from a single plasticizer system to a two-composite plasticizer system. Has no such phenomenon. This indicates that the starch esters of the example and the comparative example are different.

Table 1> crfi- 1¾ 試 trial ^

 Temperature Reaction efficiency Effectiveness Degree of substitution Number average molecular weight

(.C) (%) {%)

1 95 50 2.5 4 .53 X] L 0 ⁴

2 92 57 2.3 4 .3 1 X] L 0 ⁴

3 72 8 1 1.95.52 X] L 0 ⁴

4 79 56 2.1 4 .98 X] L 0 ⁴

5 85 8 1 2.1.6.5 1 X] ί 0 ⁴

6 96 50 2.2 4 .5 1] ί 0 '

7 20 8 1 50 2.14.44 X] ί 0 ⁴

40 89 50 2.3.4.66 X] ί 0 ⁴ cases

1 00 95 50 2-5 5.5 .54 1 L 0 ⁴

1 20 92 50 2.5 6. 1 1 X] ί 0 ⁴

1 50 92 50 2.5 7.72 x 1 L 0 ⁴

8 98 50 2.2 4.48 x 1 L 0

9 95 50 2.4 4 .66 X] ί 0

1 0 77 50 2.3.4.5 8 1 {0 ⁴

1 80 42. 2 2. 1 3.37 X] L Ο ⁴

2 8 1 43. 8 1. 8 3 . 40 X] L 0 4 ratio

3 20 75 42.2 1.7 3.2 1 X] L 0 ⁴ comparison 40 75 42.2 2.12 2.85 X] L Ο ⁴

1 00 82 42. 2 2. 3 1 .99 X] 1 Ο ⁴ examples

1 20 85 42.2 2.3 1 .53 X] 1 〇 ⁴

1 50 79 42. 2 2. 2 1. 09] L Ο ⁴

4 67 42. 2 0. 8 4 .24 X] L 0 ^Λミ ミ ロ ー ロ ー. 4. 05 X] L Ο ⁴ <Table 2>

(Tensile strength / Bending strength)

 * Unit = K g f / cm '

<Table 3>

* Unit = K gf / cm '' Table 4> Plasticizer Single Use Application Example 3 Comparative Application Example 3 Triacetin Flexural Modulus 50948 49929

(T A) Bending strength 523 460

D P B Flexural modulus 52677 51097 Curve XI Brilliance ¾ 3S I 麽 S.τ U * x

A T E C Flexural modulus 53408 51272

Cm ri 5 Ax. 丄 u L

E P E G Flexural modulus 58663 56316 Bending ¾ 1 * x * 7 Plasticizer combined (1/1 mixture)

D B P / T A Flexural modulus 50975 50039 Bending strength 628 492

A T E C / T A Flexural modulus 55 316 51 148 Bending strength 610 441

E P E G / T A Flexural modulus 56 112 54 826 Bending strength 617 461

Claims

The scope of the claims 1. A method for producing a starch ester using vinyl ester as an esterification reagent,  A method for producing a starch ester, wherein a vinyl ester having 2 to 18 carbon atoms in an ester group is used, and the vinyl ester is reacted with starch in a non-aqueous organic solvent using an esterification catalyst.  2. The method for producing a starch ester according to claim 1, wherein the number average molecular weight of the starch ester is larger than the number average molecular weight of the raw starch used.  3. The method for producing a starch ester according to claim 1, wherein the vinyl ester is used as the non-aqueous organic solvent when the vinyl ester is in a liquid state (including the one melted by heating).  4. The method for producing a starch ester according to claim 2, wherein said vinyl ester is used as said non-aqueous organic solvent when said vinyl ester is in a liquid state (including one melted by heating).  5. The method according to claim 1, wherein the non-aqueous organic solvent is  (1) starch-soluble organic solvent, and  ② starch-insoluble, vinyl ester / starch ester soluble (compatible) organic solvent,  A method for producing a starch ester.  6. In Claim 2, wherein the non-aqueous organic solvent is  ① starch soluble organic solvent, and / or  ② starch-insoluble, vinyl ester / starch ester soluble (compatible) organic solvent, A method for producing a starch ester. 7. The method for producing a starch ester according to claim 1, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  8. The method for producing a starch ester according to claim 2, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  9. In claim 3, the degree of substitution (DS) of the starch ester is 1. A method for producing a starch ester which is 0 or more.  10. The method for producing a starch ester according to claim 4, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  1 1. The method for producing a starch ester according to claim 5, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  1 2. The method for producing a starch ester according to claim 6, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  1 3. The method according to claim 1, wherein the esterification catalyst comprises: (1) an alkali, an alkaline earth metal, a hydroxide and Z of a metal belonging to an amphoteric metal, or a mineral acid, carbonate, or organic acid salt; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as minopyridine, and an amino compound such as quaternary ammonium salt.  1 4. The method according to claim 2, wherein the esterification catalyst comprises: (1) hydroxides and metals of metals belonging to alkali, alkaline earth, amphoteric metals or mineral acid salts, carbonates, or organic acid salts; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as pyridine, and an amino compound such as a quaternary ammonium salt. 1 5. The method according to claim 3, wherein the esterification catalyst comprises: (1) an alkali • an alkaline earth metal; Salts, carbonates, or organic acid salts; (2) organic interlayer transfer catalysts such as dimethylaminoviridine; and (3) amino compounds such as quaternary ammonium salts. A method for producing a starch ester, which is selected from any of them.  16. The method according to claim 4, wherein the esterification catalyst is selected from the group consisting of (1) an alkali, an alkaline earth metal, a hydroxide and a metal of a metal belonging to the amphoteric metal, a mineral acid carbonate, a carbonate, or an organic acid salt; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as pyridine, and an amino compound such as a quaternary ammonium salt.  17. The esterification catalyst according to claim 5, wherein the esterification catalyst comprises: (1) an alkali, an alkaline earth metal, a hydroxide and Z of a metal belonging to an amphoteric metal, or a mineral acid, carbonate, or organic acid salt; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as pyridine, and an amino compound such as quaternary ammonium salt.  18. The method according to claim 6, wherein the esterification catalyst comprises: (1) an alkali, an alkaline earth metal, a hydroxide and a metal of a metal belonging to the amphoteric metal, or a mineral acid, carbonate, or organic acid salt; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as pyridine, and an amino compound such as quaternary ammonium salt. 19. The method of claim 7, wherein the esterification catalyst comprises: (1) an alkali, an alkaline earth metal, a hydroxide and / or a mineral acid, a carbonate, or an organic acid salt of a metal belonging to the amphoteric metal; An organic interlayer transfer catalyst such as minopyridine, and ③ an amino compound such as quaternary ammonium salt A method for producing a starch ester, which is selected from the group consisting of:  20. The esterification catalyst according to claim 8, wherein the esterification catalyst comprises: (1) an alkali, an alkaline earth metal, a hydroxide and a metal of a metal belonging to the amphoteric metal, or a mineral acid, carbonate, or organic acid salt; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as pyridine, and an amino compound such as quaternary ammonium salt.  21. The method according to claim 9, wherein the esterification catalyst comprises: (1) hydroxides and / or mineral acid salts, carbonates, or organic acid salts of metals belonging to alkaline, alkaline earth and amphoteric metals; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as pyridine, and an amino compound such as quaternary ammonium salt.  22. The method according to claim 10, wherein the esterification catalyst comprises: (a) a hydroxide, a metal salt, a carbonate, or an organic acid salt of a metal belonging to an alkaline, alkaline earth, or amphoteric metal; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as dimethylamino pyridine, and an amino compound such as a quaternary ammonium salt. 23. In claim 11, wherein the esterification catalyst comprises: (a) a hydroxide and / or a mineral, carbonate, or organic acid salt of a metal belonging to alkali, alkaline earth, amphoteric metal; A process for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as dimethylaminopyridine, and an amino compound such as a quaternary ammonium salt. 24. The method according to claim 12, wherein the esterification catalyst is selected from the group consisting of (1) alkaline and alkaline earth metal hydroxides and metals, or salts of minerals, carbonates, or organic salts of amphoteric metals; A method for producing a starch ester, which is selected from the group consisting of an organic interlayer transfer catalyst such as dimethylamino pyridine, and an amino compound such as a quaternary ammonium salt.  25. The method for producing a starch ester according to any one of claims 13 to 24, wherein the raw material starch is previously impregnated with the esterification catalyst.  26. A starch ester produced by using a vinyl ester as an esterification reagent,  A starch ester obtained by reacting starch with a starch using an esterification catalyst in a non-aqueous organic solvent, wherein the vinyl ester has 2 to 18 carbon atoms in the ester group.  27. The starch ester according to claim 26, wherein the number average molecular weight of the starch ester is larger than the number average molecular weight of the raw starch.  28. The starch ester according to claim 26, wherein the vinyl ester is used as the non-aqueous organic solvent when the vinyl ester is in a liquid state (including a heated and melted one).  29. The starch ester according to claim 27, wherein the vinyl ester is used as the non-aqueous organic solvent when the vinyl ester is in a liquid state (including a heated and melted one).  30. The method according to claim 26, wherein the non-aqueous organic solvent is  ① Starch soluble organic solvent, and Z or ② Starch insoluble, vinyl ester 'starch ester soluble (compatible) organic solvent, A starch ester.  3 1. In claim 27, wherein the non-aqueous organic solvent is  ① starch soluble organic solvent, and or  ② starch-insoluble, vinyl ester / starch ester soluble (compatible) organic solvent,  A starch ester.  32. The starch ester according to claim 26, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  33. The starch ester according to claim 27, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  34. The starch ester according to claim 28, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  35. The starch ester according to claim 29, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  36. In claim 30, the degree of substitution (DS) of the starch ester is 1. A starch ester which is not less than 0.  37. The starch ester according to claim 31, wherein the degree of substitution (DS) of the starch ester is 1.0 or more.  38. The esterification catalyst according to any one of Claims 26 to 37, wherein the esterification catalyst comprises: (1) an alkali metal, an alkaline earth metal, or an amphoteric metal which is a hydroxide and / or a mineral acid, a carbonate, or an organic acid salt. A starch ester which is selected from the group consisting of: (2) an organic interlayer transfer catalyst such as dimethylamino pyridine; and (3) an amino compound such as a quaternary ammonium salt. 39. The starch ester according to any one of claims 26 to 37, and at least one ester type having high compatibility with the starch ester. Starch ester composition comprising a plasticizer and all or main components 40. A starch ester composition comprising the starch ester according to claim 38 and at least one or more ester-type plasticizers having high compatibility with the starch ester, as a total component or a main component.  41. The starch ester composition according to claim 39, wherein the ester plasticizer is a polyhydric alcohol fatty acid ester, wherein the fatty acid is a saturated or unsaturated fatty acid having 7 or less carbon atoms.  42. The starch ester composition according to claim 40, wherein the ester-type plasticizer is a polyhydric alcohol fatty acid ester, wherein the fatty acid is a saturated or unsaturated fatty acid having 7 or less carbon atoms.  43. The method according to claim 39, wherein the ester-type plasticizer is an organic acid ester or an inorganic acid ester of a monovalent alcohol, and at least one of the alcohol residues is an alkyl or alkenyl having 5 or less carbon atoms. A starch ester composition which is the base.  44. The method according to claim 40, wherein the ester-type plasticizer is an organic acid ester or an inorganic acid ester of a monovalent alcohol, and at least one of the alcohol residues is an alkyl or alkenyl group having 5 or less carbon atoms. A starch ester composition that is:  45. The starch ester according to any one of claims 26 to 37, and, if necessary, a plasticizer, a biodegradable polyester, a polyvinyl alcohol, a polyvinyl ester, a polyalkylene oxide, a boronamide compound, and acetic acid. A starch ester composition comprising one or more selected from cellulose as a total component or a main component. 46. The starch ester according to claim 38 and, if necessary, a plasticizer, biodegradable polyester, polyvinyl alcohol, and polyvinyl alcohol. And a starch ester composition comprising one or more selected from among esters, polyalkylene oxides, polyamide compounds, and cellulose acetate.  47. The starch ester composition according to claim 39, wherein one or two or more organic fillers and / or inorganic fillers having a fibrous form, a columnar form, a plate-like form, or a granular form are blended. .  48. The starch ester according to claim 40 to 44, wherein one or more of an organic filler having a fibrous form, a columnar form, a plate-like form or a granular form, and one or more inorganic fillers are blended. Composition.  49. The starch ester composition according to claim 45, wherein one or two or more organic fillers and fibrous or inorganic fillers having a fibrous form, a columnar form, a plate-like form, or a granular form are blended.  50. The starch ester composition according to claim 46, wherein one or two or more organic fillers and fibrous or inorganic fillers having a fibrous form, a columnar form, a plate-like form, or a granular form are blended. .